Malicious exosomes

Nanovesicles known as exosomes are secreted from a variety of cell types and circulate in biological fluids such as urine and plasma. These exosomes “hijack” membrane components and cytoplasmic contents of these cells and play an important role in intercellular communication, often inducing physiological changes in recipient cells by transferring bioactive lipids, nucleic acids, and proteins (1). These tiny vesicles also have been implicated in a number of human diseases, including cancer, and are becoming an appreciated fundamental aspect of tumor progression and metastasis (2). Recently, Melo et al. (3) showed that exosomes from breast cancer cells transfer microRNAs (miRNAs) to normal cells and stimulate them to become cancerous. This potentially expands the mechanisms by which cancer spreads and may provide opportunities to develop exosome-based diagnostics and therapies.